The present apparatus is an improvement of the device of my previously granted U.S. Pat. No. 3,834,240 dated Sept. 10, 1974.
As set out in U.S. Pat. No. 3,834,240, the practice of mouth pipetting liquid samples can be harmful and, in many laboratories, such practice has been prohibited. The mechanical devices which have been developed for this purpose such as illustrated by U.S. Pat. Nos. 3,719,087 and 3,656,351 overcome this problem but are cumbersome to operate and can cause a fatigue problem particularly when it is necessary to use these devices for long periods of time. Although the device of U.S. Pat. No. 3,834,240 constitutes an improvement over previously patented devices of this general nature, I have now found that it is possible to provide apparatus having features which constitute improvements over my previously granted patent.
It is an object of this invention to provide apparatus for drawing liquids into, and expelling liquids from, a pipette which is of simple, compact construction, the apparatus being of light weight construction and comfortably held and operated by the user for long periods of time without fatigue.
Another object is to provide apparatus of the character described having a pistol-grip portion to which is connected a pipette-supporting portion which is adapted to hold a variety of sizes of pipettes.
A further object is to provide apparatus of the character described wherein the pistol grip means is provided with a pair of valves underlying the fingers of the user which are connected to pressure and vacuum sources respectively, for selectively controlling the admission of liquid into, and the emission of liquid from a pipette.
A still further object is to provide apparatus of the character described having a pipette holder portion which is provided with valve means for permitting free passage of air to and from the pipette, but which positively prevents liquid from being drawn interiorly of the apparatus.
A further object is to provide apparatus of the character described comprising a minimum of parts which, by virtue of the present arrangement in the apparatus may be readily replaced as needed.
Other objects will be apparent from the following description of the presently preferred form of this invention taken in connection with the appended drawings.